Although Lewis Hamilton and Mercedes management are not saying precisely what is holding up his new deal, others think they know.

It could be the price or it could be the length of time with suggestions that the driver is requesting a two-year deal and the team wanting his signature for three.

Hamilton’s contract runs out this year and one UK newspaper this week reported that the defending world champion will walk away from Formula 1 in 2020 to begin a music career, according to driver-turned-pundit David Coulthard.

The British driver has been elusive about when he will sign the new one - reportedly worth a staggering BD60m over three years - while head of motorsport Toto Wolff hasn’t given a date either.

“I can only imagine that a delay can only involve money. And I should think it’s such a grotesque amount of money that Toto’s talking about, it probably is what’s making his eyes water,” Red Bull team principal Christian Horner suggested.

“Hamilton’s got an expensive lifestyle. He’s a four-time world champion and I doubt he’s cheap. I can only envisage that that’s probably got something to do with the delay.”

When asked about the contract recently, Hamilton was casual-sounding about not being rushed, saying ‘if it’s not ready this week, and it’s not ready the week after, (then) it’s not ready’.

Hamilton gives the impression he alone decides when to sign. Wolff says this is not so, yet gives no deadline.

“This is work in progress and we see no hurry to pressurise each other into signing a document that will eventually happen anyway,” Wolff said. “It is in the process of just closing. There is a bit of email ping-pong on details. I don’t want to set a date because then you will be asking: ‘Why hasn’t it been done?’”

There is uncertainty surrounding the future of other F1 drivers, too.

Hamilton’s Mercedes teammate, Valtteri Bottas, is fighting for a new deal next season, and Red Bull’s Daniel Ricciardo is considering his options for 2019. McLaren is hoping two-time F1 champion Fernando Alonso stays, while Ferrari must decide whether to stick with Kimi Raikkonen. The veteran Finnish driver turns 39 in October, but has started the season well.

Hamilton has also spoken in the past of his fondness for Ferrari, prompting speculation he could drive alongside Vettel next season. “I wouldn’t mind,” Vettel said when asked if he would like Hamilton for a teammate. He added: “I’m pretty sure that Lewis’ priority lies with Mercedes. Everything else would be a big surprise.”

Hamilton joked that a move to Ferrari ‘wouldn’t happen’ because Vettel has a veto on who joins.

Red Bull and McLaren, meanwhile, face uncertainty over their drivers.

As well as driving for McLaren this season, Alonso will race in the famed Le Mans 24 Hours endurance race taking place on June 16 & 17. In January, he took part in the 24 Hours at Daytona. Last year, the 36-year-old Spaniard skipped Monaco to race in the Indianapolis 500, and plans to race in it again.

Last weekend Toyota driver Alonso topped the times at the official Le Mans test day on his first experience of the track.

The two-time Formula 1 world champion ended up fastest in both sessions in the #8 Toyota TS050 HYBRID. Alonso improved on his 3m21.468s morning best in the afternoon, setting a time of 3m19.066s to leapfrog back ahead of team mate Kamui Kobayashi in the #7 Toyota by almost a second.

Alonso said: “It was a lot of fun out there - the track is beautiful and fits perfectly with the LMP1s. It was enjoyable for me and we got the info we needed from the test.”

Alonso has said he considered quitting Formula 1 at the end of last season. In the wake of three years of poor results with struggling McLaren, the Spaniard pondered switching full-time to IndyCar or endurance racing.

However, he said: “I felt it was not the time for me to step out - not after these results, not with this feeling. I knew I’d regret it for the rest of my life and I’d have this bad taste for the rest of my racing career.”

And, so it has proved. He described his drive in the recent Azerbaijan Grand Prix, in which he took a badly damaged McLaren to a seventh-place finish, as ‘one of the best races of my life’.

“It’s usually around the summer time that things start really taking shape,” McLaren executive director Zak Brown said. “Fernando will let us know what he wants to do pretty soon.”

Ricciardo has been linked with Mercedes and Ferrari, with both teams offering him a more powerful car unless Red Bull improves. “Daniel is fully aware that we (want) to make the best choices for the future regarding the power unit (engine),” Horner said. “He is very comfortable in the team. So once the engine scenario is sorted I think things will move reasonably quickly.”

And, the future of Romain Grosjean and Kevin Magnussen at Haas will not be considering until after the summer break, with team principal Gunther Steiner not thinking about the team’s driver line-up for the 2019 season.

F1 race action returns this coming Sunday with all eyes on the Canadian Grand Prix.

Jumping from his Monaco win to racing at another circuit he loves, Montreal, Ricciardo is hoping he can start chasing down the championship leaders.

In the last race he claimed his first victory on the streets of Monte Carlo, nursing an under-powered RB14 to the chequered flag. “After winning in Monaco it’s awesome to be going straight to another street circuit that I love,” he added.

The Canadian Grand Prix track has good memories for Ricciardo as it was in Montreal where he claimed his first ever grand prix win. He fought from sixth on the grid to beat Nico Rosberg to the line back in 2014.

This year he’s hoping to add a second Canadian win to his tally as he looks to chase down Hamilton and Vettel in the Drivers’ standings.

“It’s definitely one of my favourite races of the year, both because of the track and also the city of Montreal itself,” he said. “The city is just awesome. I’ve had some mixed results in the race but I did win my first Grand Prix there in 2014 and had a podium last year.

“Hopefully we can have another strong weekend and start chasing down the championship leaders.”